diff --git a/compiler/kernel-primitives.rkt b/compiler/kernel-primitives.rkt
index 357f8d3..ac13bab 100644
--- a/compiler/kernel-primitives.rkt
+++ b/compiler/kernel-primitives.rkt
@@ -115,6 +115,9 @@
                                     'hash-values
                                     
                                     'string-copy
+
+                                    'unsafe-car
+                                    'unsafe-cdr
                                     ))
 (define-predicate KernelPrimitiveName? KernelPrimitiveName)
 
diff --git a/js-assembler/runtime-src/baselib-primitives.js b/js-assembler/runtime-src/baselib-primitives.js
index 16a661c..db35943 100644
--- a/js-assembler/runtime-src/baselib-primitives.js
+++ b/js-assembler/runtime-src/baselib-primitives.js
@@ -587,6 +587,13 @@
             return baselib.lists.listRef(lst, baselib.numbers.toFixnum(index));
         });
 
+    installPrimitiveProcedure(
+        'unsafe-car',
+        1,
+        function (M) {
+            var firstArg = checkAny(M, 'unsafe-car', 0);
+            return firstArg.first;
+        });
 
     installPrimitiveProcedure(
         'car',
@@ -610,6 +617,15 @@
             var firstArg = checkCadrPair(M, 'cadr', 0);
             return firstArg.first.rest;
         });
+
+    installPrimitiveProcedure(
+        'unsafe-cdr',
+        1,
+        function (M) {
+            var firstArg = checkAny(M, 'unsafe-cdr', 0);
+            return firstArg.rest;
+        });
+
     installPrimitiveProcedure(
         'cdr',
         1,